Sumatriptan is a selective agonist of 5-HT_1B and 5-HT_1D receptors. It has been suggested that the binding of sumatriptan to these receptors induces vasoconstriction. This needle-free, subcutaneous (SC) injectable formulation of sumatriptan was approved on July 15, 2009, for the acute treatment of migraine attacks with or without aura and for the acute treatment of cluster headache episodes.

Efficacy. The efficacy of SC sumatriptan was assessed in several trials in patients with migraine or cluster headaches. In 2 trials of 1,104 patients with moderate or severe migraine pain, 70% (Studies 1 and 2) of patients treated with SC sumatriptan 6 mg experienced a reduction in pain from severe or moderately severe to mild or no headache within 1 hour of drug administration versus 18% (Study 1) and 26% (Study 2) of placebo-treated patients (P<.05). At 2 hours, 81% (Study 1) and 82% (Study 2) of SC sumatriptan-treated patients had headache relief versus 31% (Study 1) and 39% (Study 2) of placebo-treated patients (P<.05). The efficacy of SC sumatriptan 6 mg for the treatment of cluster headache was assessed in 2 randomized, double-blind, placebo-controlled, 2-period crossover trials. In Study 1, 74% of SC sumatriptan-treated patients experienced headache relief at 15 minutes after injection compared with 26% of placebo-treated patients (P<.05); in Study 2, 75% of SC sumatriptan-treated patients had headache relief at 15 minutes after injection compared with 35% of placebo-treated patients (P<.05).

Safety. Serious adverse cardiac events have been reported within a few hours after administration of sumatriptan. These events have included acute myocardial infarction, life-threatening disturbances of cardiac rhythm, and death. This agent can cause coronary vasospasm. SC sumatriptan should not be administered to patients with unrecognized CV disease as indicated by the presence of risk factors such as hypertension, hypercholesterolemia, smoking, obesity, diabetes, family history of CV disease, menopause (women), or age >40 years (men) unless testing demonstrates that the patient is reasonably free of underlying CV disease. Patients treated with SC sumatriptan often experience sensations of tightness, pain, pressure, and heaviness in the precordium, throat, neck, and jaw after drug administration. Some patients treated with this agent have experienced cerebral hemorrhage, subarachnoid hemorrhage, stroke, and other cerebrovascular events; some of these events have resulted in death. 5-HT₁ receptor agonists have been reported to cause vasospastic reactions other than coronary artery vasospasm, including peripheral vascular ischemia and colonic ischemia. Serotonin syndrome may occur during treatment with triptans, especially when these agents are used concomitantly with selective serotonin reuptake inhibitors (SSRIs) or serotonin norepinephrine reuptake inhibitors (SNRIs). Concomitant use of SC sumatriptan and an MAO-A inhibitor is not recommended. Patients treated with SC sumatriptan have rarely experienced hypersensitivity reactions. Rarely, patients have experienced seizures after sumatriptan treatment. The most common adverse events associated with SC sumatriptan treatment include injection-site reactions, tingling sensation, dizziness/vertigo, warm/hot sensation, flushing, burning sensation, feeling of heaviness, and pressure sensation.

Dosing. SC sumatriptan should be self-administered by the patient only to the abdomen or thigh. One unit of this agent (containing sumatriptan 6 mg) should be administered; the maximum recommended dose over 24 hours is 2 doses (units) separated by ≥1 hour. The dose should not be administered within 2 inches of the navel. Each unit is for single use only.